A novel formulation of wind velocity spectrum incorporating rainfall influence

Abstract

Wind-rain interaction constitutes a common physical phenomenon in nature. Nevertheless, in fluid mechanics and wind engineering, whether and how rainfall influences wind remains an unresolved challenge. This study relies on a substantial dataset obtained through on-site measurement. Initially, three distinct rainfall categories—light rain, moderate rain, and heavy rain—are established based on the magnitude of vertical wind velocity. Notably, significant disparities in the high-frequency constituents of the fluctuating wind velocity spectrum are discerned across various rainfall levels. Subsequently, a rigorous quantitative analysis explores the relationship between the high-frequency cumulative energy proportion of the fluctuating wind velocity spectrum and rainfall intensity, leading to formulations that delineate the high-frequency cumulative energy proportion in the alongwind, acrosswind, and vertical wind directions as explicit functions of rainfall intensity. Moreover, a comprehensive unified expression models the three-dimensional fluctuating wind velocity spectrum. This expression incorporates parameters encompassing the relative scales of fluctuation and mean components, the extent of conversion between high and low-frequency energy, and the scaling laws governing the inertial subrange. Additionally, explicit functional dependencies for these parameters concerning variations in rainfall intensity are provided. The novel formulation of the fluctuating wind velocity spectrum proposed in this study bears substantial scientific significance, as it facilitates a deeper understanding of wind-rain interaction and offers valuable insights for conducting intricate environmental flow field simulations.